WASHINGTON (Reuters) - The U.S. military carried out freedom of navigation operations challenging the maritime claims of China, Iran and 10 other countries last year, asserting its transit rights in defiance of efforts to restrict passage, a Pentagon report said on Thursday.
The Defense Department's annual Freedom of Navigation Report to Congress for the 2013 fiscal year showed the U.S. military targeted not only countries such as Iran, with whom it has no formal relations, but treaty allies such as the Philippines, too.
The U.S. military conducted multiple operations targeting China over what Washington believes are "excessive" claims about its maritime boundaries and its effort to force foreign warships to obtain permission before peacefully transiting its territorial seas.
U.S. operations challenging Iran were aimed at rejecting Tehran's effort to restrict the Strait of Hormuz to ships from nations that have signed the U.N. Convention on the Law of the Sea, an accord the United States has not formally adopted.
The report covers activity in the 2013 fiscal year that ended September 30, before the latest tensions over a near mishap between U.S. and Chinese warships in the South China Sea and Beijing's declaration of an air defense identification zone over the East China Sea, which Washington rejected.
The United States carries out freedom of navigation operations by sending Navy ships into disputed areas in an effort to show that the international community has not accepted claims made by one or more countries.
The operations, which began in 1979, are coordinated by the State and Defense departments and are meant to be consistent with the U.N. Law of the Sea Convention, even though Washington has not formally adopted the agreement.
"The United States will not ... acquiesce in unilateral acts of other states designed to restrict the rights and freedoms of the international community in navigation and overflight," the Pentagon said in a 1992 Freedom of Navigation report by then-Secretary of Defense Dick Cheney.
U.S. operations in the 2013 fiscal year also challenged claims by Cambodia, India, Indonesia, Libya, Malaysia, Maldives, Oman, Taiwan and Vietnam. All countries but Cambodia were targeted more than once.
Since 1991, the United States has conducted more than 300 freedom of navigation operations challenging maritime claims by 53 different countries worldwide, from Albania, Ecuador and Denmark to Pakistan and Yemen.
Iran and the Philippines have been challenged most frequently. Iran has appeared on 19 of the 21 lists submitted to Congress since 1991, while the Philippines has appeared on 18. Cambodia, the Maldives, India and Oman also frequently appear.
China has been on the list 11 times, the same as Indonesia and one less than Burma.
The most frequent U.S. complaint is with countries that measure the start of their territorial waters by drawing a straight line between two points on the coast or along offshore islands, thereby enclosing a vast expanse of sea.
Washington disagrees with the Philippines' designation of the seas bounded by the island chain as internal waters and therefore off limits to foreign ships or overflight by foreign aircraft.
The United States targets about a dozen countries per year for challenge, with the high ranging to 27 countries in 1998 and dropping into the low single digits at the height of the U.S. war in Iraq.
Editing by Ken Wills